PPP2R1B gene alterations inhibit interaction of PP2A-Abeta and PP2A-C proteins in colorectal cancers

Oncol Rep. 2004 Mar;11(3):655-9.


The chromosome region 11q is frequently deleted in colorectal cancers. The PPP2R1B tumor suppressor gene, encoding the beta isoform of the A subunit of serine/threonine-specific protein phosphatase 2A (PP2A-Abeta), located at 11q22-23, is inactivated in patients with cancer. The present study investigated whether or not PP2A-Abeta is altered in colorectal cancers. We searched for alterations of the PPP2R1B gene and interactions between PP2A-Abeta and PP2A-C proteins in 50 surgically resected colorectal cancer tissues. Missense mutations and homozygous deletions of the PPP2R1B gene were found in 4 of 50 patients (8%) and in 1 of 50 patients, respectively, with colorectal cancers. Deletions and/or point mutations within 412-601 amino acid sequences (binding regions of PP2A-C protein) of the PPP2R1B gene derived from colorectal cancer tissues inhibited co-immunoprecipitation of PP2A-Abeta and PP2A-C proteins. These finding suggested that the PPP2R1B gene functions as a tumor suppressor gene and acts as a molecular switch that becomes active in response to specific up-stream signals. Upon activation, the gene alters the activities of specific downstream target proteins for the cell cycle regulations and/or metabolism in some colorectal cancers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle
  • Cell Line, Tumor
  • Codon
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / metabolism*
  • DNA / metabolism
  • Gene Deletion
  • Homozygote
  • Humans
  • Loss of Heterozygosity
  • Mutation*
  • Mutation, Missense
  • Neoplasm Proteins / genetics*
  • Neoplasm Proteins / physiology*
  • Phosphoprotein Phosphatases / genetics*
  • Phosphoprotein Phosphatases / metabolism*
  • Point Mutation
  • Polymorphism, Single-Stranded Conformational
  • Precipitin Tests
  • Protein Binding
  • Protein Phosphatase 2
  • Signal Transduction
  • Transcription, Genetic


  • Codon
  • Neoplasm Proteins
  • PPP2R1B protein, human
  • DNA
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 2